Alternative desktop environments as fallback for Gnome 3

Summary

There are many people whose hardware can't run Gnome Shell, which is Gnome 3's defining user interface. While Gnome 3 contains a fallback interface, it has clearly been stated that it won't be developed further and isn't intended to provide any good user experience. These users are many and however they can solve their problem by manually installing an alternative desktop environment, in order to help these users and provide a good default user experience to them, we should make this automatic.

There are two possible approaches to do this (whether we should go with the first or the second needs discussion)

Detect the lack of 3D capability on first boot and present the user the option to switch to Xfce on first boot and/or installation time. See below for details.

Modify the Gnome session to launch Xfce instead its own fallback interface

Assuming that non 3D accelerated / Otherwise not capable of running gnome-shell hardware is either old hardware that would work better with a lighter DE, or has a too low amount of RAM for running gnome-shell properly (fallback mode also require a big amount of available ram as GNOME 2.32 did).

Display a dialog that explains the experience of Gnome's fallback mode, Gnome Shell, and Xfce

The dialog will select the best option for the specific hardware, but will allow the user to change the selection

When 3D acceleration is available, gnome-shell will be selected by default

When 3D acceleration is not available, or when the system doesn't have large amount of RAM, Xfce will be selected

If Xfce is not installed, it will present the option to install it

If the user selects gnome-shell, and 3D acceleration is not available, display a warning (not in a message box, but in the window itself) that gnome will start in fallback mode unless 3D acceleration is available

Benefit to Fedora

Better user experience for users with low-end hardware

Fedora could lower its minimal hardware requirements to the requirements of Xfce